System of electrical distribution.



J. H. TRACY. SYSTEM 01' ELEGTRIGAL DISTRIBUTION. APPLICATION FILEDMAE.19,190B.

902,777. Patented Nov. 3, 1 908.

WITNES 5. I N VEN TOR. N uaepfifl Tray- ATTORNEY.

JOSEPH H. TRACY, OF PHILADELPHIA, PENNSYLVANIA.

SYSTEM OF ELECTRICAL DISTRIBUTION.

Specification of Letters Patent.

Application filed March 19, 1908.

Patented Nov. 3, 1908.

Serial No. 422,133.

To all whom it may concern:

Be it known that I, JOSEPH H. TRACY, a citizen of the United States, anda resident of Philadelphia, in the county of Philadelphia and State ofPennsylvania, have invented a certain new and useful System ofElectrical Distribution, of which the following is a specification.

My invention relates to systems of distri- -bution in which bothalternating and direct current translating devices are supplied from acommon source, and in which a storage battery is installed to compensatefor the fluctuations of load on both the alternating and direct currentcircuits.

In general my invention provides apparatus for controlling the operationof the battery in response to variations in the combined output of thesource to both circuits. This and other objects as well as the generalnature of the invention will be more clearly seen by reference to thefollowing description in connection with the accompanying drawing, inwhich A is a source of direct and alternating cur rents, for example, adouble current generator provided with alternating current taps and acommutator connected to the same winding. The source A may be driven byany suitable prime mover, and as here shown is connected to thealternating current circuit 1, 2, and 3, and to the direct currentcircuit 4 and 5, to which circuits are connected respectively thetranslating devices L and L constituting fluctuating loads. A storagebattery C with its booster B is connected across the direct currentcircuit. The field F of the booster is energized by the exciter E insuchaway as to cause the battery to charge and discharge in response to variations of the total combined load on the source A.

The exciter E consists of an armature N revolving in a field frame 0,which latter is rovided with four polar projections P P f andl. Thisarmature is provided with a bi-polar winding and a commutator upon whichbear two pair of brushes 1011 and 12-13. The brushes 1213 areshortcircuited by a conductor 14 of low resistance, while the brushes1011 are connected to the field F of the booster. The poles of themachine E are provided with three field windings. One of these 7, isconnected in series with conductor 5 between the source A and thejunction of the battery branch so as to carry a current proportional tothe direct current output of the source. Winding 6, is connected inshunt across the circuit 4, 5, and may be controlled by the rheostat R.The third winding 8, is connected in series between brush 10 and thefield F. The armature winding of the exciter E, is also connected to thesecondary windings of the cur rent transformers T, T and T whoseprimaries are connected in serieswith conductors 1, 2, and 3,respectively. By this means alternating current proportional to thealternating current output of the source A is transmitted through thearmature winding of the machine E. A synchronous motor M, driven bycurrent from the alternating circuit 1, 2, 3, is shown connected to thearmature shaft of the machine E.

The operation of this apparatus is then as follows: The currenttransmitted through the armature winding of the machine E from thecurrent transformers T T T would produce a rotating field were it notfor the fact that the rotation produced by the mo-' tor M, which is inthe opposite direction to that of the field, will hold this fieldstationary in space. The connections are such that the effect of thisalternating current in the armature winding will produce a field of likepolarity, as for example north polarity, in the poles P P and of theopposite polarity in the poles P and P The series winding 7, thatcarries the direct current output from'the source A is designed toproduce a similar field in the poles of the exciter E. The number ofturns of this latter field is such that a given output in kilowatts fromthe source A to the direct current circuit 45 will produce the samefield strength, as the same output in kilowatts in the alternatingcurrent circuit 1, 2, 3 will produce by rea son of the alternatingcurrent transmitted through the armature winding. Thus, so long as thetotal output from the machine to the two circuits remains constant, thefield strength produced by the combined action of the field winding 7and of the alternating current in the armature winding will be constant.The field winding 6, is excited differentially with respect to winding7, and by means of the rheostat R, its strength may be so adjusted as toexactly neutralize the field which would otherwise be produced with somepredetermined combined load on the source A, so that the field strengthwill be zero when the total load on the source A is equal to thispredetermined value. Under these conditions the voltage between thebrushes 12 and l3 will be ZOI'O and no current will flow between thesebrushes through the conductor 14. Any increase in the total output fromthe source A, whether to the alternating current or to the directcurrent circuit will cause the combined excitation due to thealternating current in the armature andthe direct current in fieldwinding 7 to predominate over that of the shunt field winding 6, thusproducing a field whose axis is in a line joining brushes 1.0 and 11.,and this field. will produce a voltage between the brushes 12 and 18. Avery small change in the total load on the source A producing a verysmall voltage between the brushes 1.2 and 13, will cause a How ofcurrent between the latter brush of considerable magnitude on account of"the low resistance of conductor 14., and this current flowingtl'irougl'i the armature winding will produce'a second field ofconsiderable magnitude, whose axis will be in the line joining thebrushes 12 and. 13, and this field will produce a voltage ofconsiderable magnitude across the brushes 10 and 11, which will sendcurrent through the field F of the booster to cause the battery todischarge. Similarly a small decrease in the output from the source Awill cause the excitation of the shunt field 6, to predominate producinga net field and [low of current be tween brushes 12 and 1.3 in theopposite di rection and a reversal of the booster voltage, causing thebattery to charge. The field winding 8, which is in series between brush10 and the field winding F, serves to neutralize the armature re-actiondue to a How of current in the armature winding between brushes 10 and11, preventing this fiow of current from having any appreciable eilecton the voltage.

It will be obvious to those skilled in the art that modifications may bemade in details without departing from the spirit of the invention,hence I do not limit the invention further than the prior state of theart may require, but having thus described the nature and object of myinvention hat I claim as new and desire to secure by Letters Patent is:

1. In combination an alternating current circuit, a direct currentcircuit, a source of electrical energy connected. to both circuits, astorage battery operatively arranged in respect to the source, a fieldstructure and in inductive relation thereto an arnuiture provided with awinding, commutator and brushes, means for transmitting through thearmature winding alternating currents proportional to the alternatingcurrent output from the source, means for producing a field excitationproportional to the direct current output from the source, andconnections from the brushes for controlling the charge andv dischargeof the battery responsively to changes in the combined alternatingcurrent and direct current excitation.

2. In combination an alternating current circuit, a direct currentcircuit, a source of electrical energj connected to both circuits, astorage battery operatively arranged with respect to the direct currentcircuit, a field structure with appropriate field windings and ininductive relation thereto an armature provided with a winding and aeominutator, means for transmitting through the armature winding and thefield windings currents proportional respectively to the alternatingcurrent and the direct current output from the source to produce aresultant field, a set of electrically interconnected brushes bearing onthe :onnnutator and appertaining to said resultant field and adapted topermit a flow of current through the arnntture winding to produce asecond field displaced from the first and responsive thereto, a secondset of brushes appertaining to the second field, and connections fromthe second set of brushes for controlling the operation of the battery.

3. In combination an alternating current circuit, a direct currentcircuit, a source of electrical energy connected to both circuits,

a storage battery operativcly arranged with respect to the directcurrent circuit, a field structure with appropriate field windings and.in inductive relation thereto an armature provided with a winding and acommutator, means for transmitting through the armature winding and thefield windings cur rents proportional respectively to the alternatingcurrent and the direct current output from the source to produce aresultant field, a set of electrically interconnected brushes bearing onthe commutator and ap ertaining to said, resultant field, and adapted topermit a How of current through the armature winding to produce a secondfield. displaced from the first and responsive thereto, a second set ofbrushes appertaining to the second field, connections from the secondset 01. brushes for controlling the operation of the battery, and meansfor producing relative rotation of armature and field in synchronismwith the source.

4:. In combination an alternating current circuit, a direct currentcircuit, a source of electrical energy connected to both circuits, a

storage battery and booster operatively arranged with respect to thedirect current circuit, a field structure with appropriate fieldwindings and in inductive relation thereto an armature provided with awinding and a commutator, means for transmitting through the armaturewinding and the field windings currents proportional respectively to thealternating current and the direct current output from the source toproduce a resultant field, a set of electrically interconnectedelectrical energy connected to both circuits,

a storage battery and booster operatively arranged with respect to thedirect current circuit, a field structure with ap ropriate fieldwindings and in inductive re ation thereto an armature provided with awindin and a commutator, means for transmitting t rough the armaturewinding and the field windings currents proportional respectively to thealternating current and direct current output from the source to producea resultant field, a set of electrically interconnected brushes bearingon the commutator and appertaining to said resultant field and adaptedto permit a flow of current through the armature winding to produce asecond field displaced from the first and responsive thereto, a secondset of brushes appertaining to the second field, and connections fromthe second set of brushes for controlling the operation of the booster,and means for producing relative rotation of armature and field insynchronism with the source.

In testimony whereof I have hereunto signed my name.

JOSEPH H. TRACY. Witnesses:

J. W. AoHARD, CARROLL HoDGE.

